Biology subjects

Barbera, C.

Publications and source records attributed to Barbera, C..

4 recordsLinked to original sources

bioRxiv2025

Early warning signals of emerging infectious diseases

Establishing early warning systems for infectious disease outbreaks could save millions of lives by enabling rapid response and containment. One promising approach draws on the concept of critical slowing down (CSD)--a phenomenon in which complex systems lose resilience before tipping points--detected using resilience indicators (RIs) derived from the statistical properties of time series. While disease outbreaks may exhibit such early warning signals of critical transitions, most prior applications of CSD theory to global health have been limited to single diseases or locations, without broad assessments of predictive accuracy or lead time--the interval between the detection of warning signals and the onset of an outbreak. To address these limitations, we integrate CSD theory with time-to-event analyses to evaluate the predictive performance of 17 RIs across 31 infectious diseases in 134 regions worldwide. We find that both RIs and time- to-event analyses provide ample time to implement control measures, reliably anticipating outbreaks with a mean lead time of 17-21 days. Lead time was greater for pathogens with longer incubation periods and in regions with higher Human Development Index. Additionally, temperature and precipitation exhibited unimodal effects on lead time predictions for vector-borne and viral diseases. These findings highlight the value of incorporating socio-environmental drivers into outbreak forecasting models and lay the foundation for a local-to-global early warning system capable of guiding proactive public health interventions.

ecology↗

bioRxiv2025

Larval development habitats of Culicoides midges in the western United States

Culicoides midges are vectors of bluetongue virus (BTV), an arbovirus affecting wild and domestic ruminants. Bluetongue distribution generally overlaps with vector range, so understanding the vectors ecology is necessary for predicting BTV risk. Culicoides require moist substrate for oviposition and development, and C. sonorensis, the primary vector in the western United States, is classically associated with livestock wastewater ponds. However, it is well-known that BTV can be found outside of managed livestock areas, with transmission also occurring in natural settings. To better classify development habitat for Culicoides, we conducted a broad biweekly survey of moist and wet habitats from June to September of 2022 in northern Colorado at ten sites, including large livestock operations, non-commercial domestic operations, and natural spaces. Samples were maintained in the insectary for 11 weeks and monitored for emergence of adult midges. Standing water substrates displayed higher presence and abundance of midges than running or transient habitats, though all microhabitats showed emergence. Additionally, livestock sites did not produce more midges than other site types, and in fact more midges were observed in natural spaces per sample and overall. Livestock spaces did, however, show significantly higher proportions of C. sonorensis midges, which are thought to be the most competent vectors of BTV in this region. These results suggest that development sites in natural areas may play an important role in maintaining vector populations in the western U.S. outside of previously implicated livestock operations, and that differences in larval habitat lead to differences in vector species composition.

ecology↗

bioRxiv2022

Global change drivers and the risk of infectious disease

Anthropogenic change is contributing to the rise in emerging infectious diseases, but it remains unclear which global change drivers most increase disease and under what contexts. We amassed a dataset from the literature that includes 1,832 observations of infectious disease responses to global change drivers across 1,202 host-parasite combinations. We found that biodiversity loss, climate change, and introduced species were associated with increases in disease-related endpoints or harm (i.e., enemy release for introduced species), whereas urbanization was associated with decreases in disease endpoints. Natural biodiversity gradients, deforestation, forest fragmentation, and most classes of chemical contaminants had non-significant effects on these endpoints. Overall, these results were consistent across human and non-human diseases. Context-dependent effects of the global change drivers on disease were common and are discussed. These findings will help better target disease management and surveillance efforts towards global change drivers that increase disease. One-Sentence SummaryHere we quantify which global change drivers increase infectious diseases the most to better target global disease management and surveillance efforts.

ecology↗

bioRxiv2022

Modeling cellular co-infection and reassortment of bluetongue virus in Culicoides midges

When related segmented RNA viruses co-infect a single cell, viral reassortment can occur, potentially leading to new strains with pandemic potential. One virus capable of reassortment is bluetongue virus, which causes substantial health impacts in ruminants and is transmitted via Culicoides midges. Because midges can become co-infected by feeding on multiple different host species and remain infected for their entire life-span, there is high potential for reassortment to occur. Once a midge is co-infected, additional barriers must be crossed for a reassortant virus to emerge, such as cellular co-infection and dissemination of reassortant viruses to the salivary glands. We developed three mathematical models of within-midge bluetongue virus dynamics of increasing complexity, allowing us to explore the conditions leading to the emergence of reassortment viruses. In confronting the simplest model with published data, we estimate the average lifespan of a bluetongue virion in the midge midgut is about six hours, a key determinant of establishing a successful infection. Examination of the full model, which permits cellular co-infection and reassortment, shows that small differences in fitness of the two infecting strains may have a large impact on the frequency with which reassortant virions are observed. This is consistent with experimental co-infection studies with BTV strains with different relative fitnesses that did not produce reassortant progeny. Our models also highlight several gaps in existing data which would allow us to elucidate these dynamics in more detail, in particular the times it takes the virus to disseminate to different tissues, and measurements of viral load and reassortant frequency at different temperatures.

microbiology↗